From a Las Vegas native's point of view

Fry Sauce

Fry Sauce originated in Utah and is mostly unheard of outside of Utah and Nevada. This regional cult condiment resembles a thick Thousand Island dressing. Mainly used as a dipping sauce for French fries, Fry Sauce also turns fried onion rings, shrimp cocktail, egg salad, corned beef sandwiches and hamburgers into something special.

The original Fry Sauce was invented around 1950 by the Arctic Circle fast food chain. Their recipe is a guarded secret and uses mayonnaise as the primary ingredient. Mayonnaise with French fries is not as unusual as it may sound; in some European countries mayonnaise is the preferred condiment for fried potatoes. This recipe comes very close to the Arctic Circle version.